Understanding the Most Common HTTP Errors

It happens with us very often that we come across different error pages while browsing on the web. Have you ever wondered what these errors exactly mean? Every error page that we see is the result of some specific request or action that we implement on the server. When we access the web server or application through a HTTP request, the server responds with specific three digit status codes. By reading these codes, we can easily determine whether the request made to the server has been successful or redirected, or any client or server errors exists. The HTTP client error status codes begin with digit ‘4’. So if you see any three digit error starting with 4 then it is clear that you have encountered an client side error.
There are many reasons that can cause a web server respond to a HTTP request with a specific error. It is important to note that error pages are displayed differently in different browsers. No matter what browser you are using (Firefox, Chrome or IE), the meaning of the error message would be the same.
In this article we will cover some of the error types and their common potential causes.

Certificate Error
The SSL certificate error or security certificate error occurs only if there is a problem while browsing a website that has security encryption. In order to identify the websites as legitimate and protect users from visiting the wrong websites, many websites are given security certificates. When user tries to connect to the website through HTTPS request, the browser checks site certificate before connecting. There could be two possible reasons to encounter with certificate error – either the user is not connecting to the real, legitimate website or the website has not configured or renewed its certificate properly.

Connection error
When you try to connect to the server, you may receive “Unable to connect to the server” or “Google Chrome could not connect to the website” message. This is one of the most common errors that we often see if the site is down for any reason. It may be possible that the server could not connect because of firewall, proxy, or network issues. Sometimes, even the anitvirus or anti-spyware programs restrict the browsers from connecting if the website is not trusted.

Phishing and Malware Warnings
The phishing or malware warnings tell users that the website they are about to browse may contain malware or the site may make an attempt to steal the personal information. Many people are likely to bypass these warnings if they are regular visitors of popular websites. Even the most popular or reputed websites can be malicious, or may con the users to give away their passwords, bank details or other sensitive information. Hence, it is not a good idea to proceed with the site if we come across this error message because we may get into unnecessary troubles by downloading these malwares.

Client errors
All the client side errors start with ‘4’ as the first digit in the error status code. If we look at 400 status code, it represents ‘Bad Request’, 401 for ‘Unauthorized’, 403 for ‘Forbidden’, 404 for ‘Not found’ and so on. Among them 404 is the most common one that we generally come across when the client is unable to locate the requested file or resource on the server. It could be that the user might be trying to access the page that is not existing which means either the site is unavailable or the web address is wrong.

Server errors
These errors occurs when the browser cannot link to the server or when the server cannot process the request due to issues with website, DNS, proxy or other reasons. The HTTP status codes for server errors start with digit ‘5’, where in 500 is meant for ‘Internal server error’ , 502 for ‘bad proxy’, 503 for ‘service unavailability’, 504 for ‘Proxy or Gateway timeout’ etc.

Customized errors
Many website owners are very particular in customizing their error pages because they want to convey the proper reason for the website unavailability in a courteous manner. Sometimes they redirect the error pages to their home page or display good graphics to entertain the user. No matter what image or design they use to display the errors, all these error messages represent the same meaning.